+ // Separating Axis Theorem:
+ // if a supporting vector (plane normal) can be found that separates two
+ // objects, they are not colliding.
+ //
+ // Minkowski Sum:
+ // reduce the size of one object to a point while enlarging the other to
+ // represent the space that point can not occupy.
+ //
+ // try every plane we can construct between the two brushes and measure
+ // the distance between them.
+ for (nplane = 0; nplane < numplanes; nplane++)
+ {
+ VectorCopy(other_start->planes[nplane].normal, startplane);
+ startplane[3] = other_start->planes[nplane].dist;
+ startdist = DotProduct(linestart, startplane) - startplane[3];
+
+ if (startdist > 0)
+ return;
+
+ // aside from collisions, this is also used for error correction
+ if (startdepth < startdist || startdepth == 1)
+ {
+ startdepth = startdist;
+ VectorCopy(startplane, startdepthnormal);
+ starttexture = other_start->planes[nplane].texture;
+ }
+ }
+
+ // at this point we know the trace overlaps the brush because it was not
+ // rejected at any point in the loop above
+
+ // started inside, update startsolid and friends
+ trace->startsupercontents |= other_start->supercontents;
+ if ((trace->hitsupercontentsmask & other_start->supercontents) && !(trace->skipsupercontentsmask & other_start->supercontents) && !(trace->skipmaterialflagsmask & (starttexture ? starttexture->currentmaterialflags : 0)))